Ukrainian President Viktor Yanukovych said he had reached an agreement with opposition leaders on a “truce” to halt fighting that has killed 26 people, even as the United States stepped up pressure by imposing travel bans on 20 senior Ukrainian officials.

A statement on the presidential website announced an accord for “the start to negotiations with the aim of ending bloodshed, and stabilising the situation in the state in the interest of social peace”.

[We declare] the start to negotiations with the aim of ending bloodshed, and stabilising the situation in the state in the interest of social peace

Ukraine government statement

The two sides agreed to negotiate in an effort to end the violence that left at least 26 people dead and more than 400 injured on Tuesday. Protesters say the casualty toll is substantially higher.

The brief statement on the president’s website did not give details of the terms of the truce or how it would be implemented. Nor did it specify how the negotiations would be conducted or give an indication of how they would be different from previous meetings of the president and the opposition leaders.

Boxer turned opposition leader Vitaly Klitschko said Yanukovych assured them that police would not storm the protesters’ encampment on Kiev’s Independence Square, according to the Interfax news agency. Klitschko had walked out of talks with Yanukovych on Tuesday, saying he could not negotiate while blood was being spilled.

Perhaps crucially, there was no immediate indication of whether radical elements among the protesters would observe the truce or be mollified by the prospect of negotiations.

The intense clashes between police and protesters led Yanukovych to declare that the military would take part in a “national anti-terrorist operation”. The parameters weren’t specified, but the military’s involvement and Yanukovych’s appointment of a new military chief of staff fuelled new worries.

His security service said it had launched a nationwide “anti-terrorist operation” after arms and ammunition dumps were looted.

Watch: Kiev in flames as Obama warns of 'consequences'

'Targeted sanctions'

A tense stand-off between protesters and riot police continued early on Thursday in Kiev, where the foreign ministers of France, Germany and Poland would later hold an emergency meeting with Yanukovych before returning to Brussels for a meeting of all 28 European Union foreign ministers to decide on targeted sanctions against those deemed responsible for the violence.

Fires, used for protection, blazed around the tent camp in Kiev for a second night and protesters defending it showed no signs of yielding, but there was no immediate sign of a repetition of violence seen on Tuesday.

Yanukovych, backed by Russia, had denounced the bloodshed in central Kiev, where protesters have been dug in for almost three months since he spurned a trade deal with the EU in favour of closer Russian ties, as an attempted coup.

The president declared Thursday a day of mourning for the dead.

The violence, the worst since Ukraine’s independence from the Soviet Union 22 years ago, provoked a chorus of condemnation from the West.

EU ambassadors discussed a series of possible steps including asset freezes, travel bans and restrictions on the import of weapons in talks on Wednesday, even though some diplomats have doubts about the effectiveness of such sanctions.

Jumping out ahead of its EU allies, Washington late on Wednesday imposed US visa bans on 20 Ukrainian government officials it considered “responsible for ordering human rights abuses related to political oppression”, a senior State Department official said. Their names were not disclosed.

Yanukovych exempt from sanctions

While EU officials said they were considering targeted sanctions for the “unjustified use of excessive force by the Ukrainian authorities”, they noted Yanukovych himself would be excluded from such measures in order to keep channels of dialogue open.

Yanukovych said he had refrained from using force during three months of unrest but was being pressed by “advisers” to take a harder line. “Without any mandate from the people, illegally and in breach of the constitution of Ukraine, these politicians – if I may use that term – have resorted to pogroms, arson and murder to try to seize power,” he said.

The state security service said it had opened an investigation into illegal attempts by “individual politicians” to seize power.

Although the initial weeks of protests were determinedly peaceful, radicals helped drive an outburst of clashes with police in January in which at least three people died. And the day of violence on Tuesday may have radicalised many more.

Among those who died, some were hit by bricks or sprayed with shrapnel from stun grenades. Others were burned or struck by rubber bullets or live ammunition. Many protesters, terrified that they would be taken straight from the hospital to a police station, sought medical help at a nearby monastery, where operating tables stand near the altar.

Andrei Guk, who runs a medical centre in Mikhailovsky Cathedral, said most of the injured had shrapnel wounds or burns. Hospital staff reported seeing various types of wounds stemming from knives to pellet bullets.

Police said that many of the wounded officers suffered wounds from live ammunition, which they blamed on radical demonstrators bringing firearms into the fray. They insisted that the police carried no live ammunition and used only rubber bullets or tear gas to disperse the mob.

Demonstrators forced their way into the main post office on Kiev’s Independence Square, also known as the Maidan, after a nearby building they had previously occupied was burned down in fierce, fiery clashes late on Tuesday with riot police. Thousands of activists armed with fire bombs and rocks had defended the square.

Before the truce was announced, the bad blood was running so high that it has fuelled fears the nation could be sliding toward a messy break-up. While most people in the country’s western regions resent Yanukovych, he enjoys strong support in the mostly Russian-speaking eastern and southern regions, where many want strong ties with Russia.

Neither side had appeared willing to compromise, with the opposition insisting on Yanukovych’s resignation and an early election and the president apparently prepared to fight until the end.

Opposition lawmaker Oleh Lyashko warned that Yanukovych himself was in danger. “Yanukovych, you will end like [Muammar] Gaddafi,” Lyashko told thousands of angry protesters. “Either you, a parasite, will stop killing people or this fate will await you. Remember this, dictator!”

Ukraine’s ailing economy is a major factor in the crisis.

Ordinary Ukrainians are struggling amid a stagnating economy and soaring corruption. They have been especially angered to see that Yanukovych’s close friends and family have risen to top government posts and amassed fortunes since he came to power in 2010. Yanukovych’s dentist son, Oleksander, has become a financial and construction magnate worth US$187 million, according to Forbes Ukraine.

On Wednesday morning, the centre of Kiev was cordoned off by police, the subway was shut down and most shops on the main street were closed. But hundreds of Ukrainians still flocked to the opposition camp, some wearing balaclavas and armed with bats.

One group of young men and women poured petrol into plastic bottles, preparing fire bombs, while a volunteer walked by distributing ham sandwiches. Other activists were busy crushing the pavement into bags to fortify the barricades.

In the western Ukrainian city of Lviv, where most residents yearn for stronger ties with the EU and have little sympathy for Yanukovych, protesters seized several government buildings, including the governor’s office, police stations and offices for prosecutors, security officials and the tax agency. They also broke into an Interior Ministry unit and set it on fire.

In another western city, Lutsk, protesters handcuffed the regional governor, a Yanukovych appointee, and tied him on a central square after he refused to resign. In the city of Khmelnitsky, three people were injured when protesters tried to storm a law enforcement office.

Pressure mounts

Responding cautiously to the truce, US President Barack Obama deemed it a “welcome step forward”, but said the White House will continue to monitor the situation closely to “ensure that actions mirror words.”

Obama and Canadian Prime Minister Stephen Harper, attending a North American summit in Mexico, said they would welcome the truce if it led to a dialogue. They also said they would work with their European allies on helping resolve the crisis.

Although Washington appears to have little direct leverage in the crisis, the Obama administration has invited the leaders of Georgia and Moldova to visit Washington in the next two weeks in what appeared to be an effort to show US support for neighbours of Russia that are concerned about the crisis in Ukraine.

Apparently with an eye to possible sanctions that might have consequence for big business interests, three of Ukraine’s richest entrepreneurs have stepped up pressure on Yanukovych to hold back from use of force and make every effort to solve the crisis through negotiation with the opposition.

“There are no circumstances which justify the use of force toward the peaceful population,” steel and coal magnate Rinat Akhmetov said in a statement issued late on Tuesday.

Akhmetov, who partly bankrolled Yanukovych’s election campaign in 2010 and whose wealth is put by Forbes at more than US$15 billion, said: “People’s deaths and injuries on the side of protesters and the security forces in street battles are an unacceptable price for political mistakes.”

Viktor Pinchuk, another steel billionaire well known in the West for his philanthropic activity, said: “A peaceful solution must be found. It is imperative to refrain from the use of force and find a compromise ... It is time for all sides to take courageous steps toward compromise.”

We, through our joint actions, must end the bloodshed. We are against radical actions by whomever it might be

Dmytro Firtash, businessman

Dmytro Firtash, a gas and chemicals magnate who is part owner of a popular TV channel Inter, in a statement on Wednesday also called for a political settlement to be found which avoided use of force. “We, through our joint actions, must end the bloodshed. We are against radical actions by whomever it might be.”

Moscow had announced on Monday it would resume stalled aid to Kiev, pledging US$2 billion just hours before the crackdown began. The money has not yet arrived, and a Ukrainian government source said it had been delayed till Friday “for technical reasons”.

The Kremlin said it put the next disbursement of its bailout on hold amid uncertainty over Ukraine’s future and what it described as a “coup attempt”.

Ukraine’s hryvnia currency, flirting with its lowest levels since the global financial crisis five years ago, weakened to more than 9 per US dollar for the second time this month.